790 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



species, Coix lacryma-jobi. Name from 

 Greek koix, a kind of palm, applied 

 by Linnaeus to this grass. 



1. Coix lacryma-jobi L. Jobs- 

 tears. (Fig. 1194.) Annual; culms 

 usually about 1 m. tall; blades as 

 much as 4 cm. wide; beads white to 

 bluish gray, globular or ovoid, 6 to 

 12 mm. long. O — Occasionally 



cultivated for ornament, escaped into 

 waste places in the Southern States; 

 all tropical countries; introduced in 

 America. The beadlike fruits are 

 used as beads and for rosaries. A 

 garden form (called by gardeners var. 

 aurea zebrina) has yellow-striped 

 blades. 



166. TRIPSACUM L. Gamagrass 



Spikelets unisexual; staminate spikelets 2-flowered, in pairs on one side of a 

 continuous rachis, one sessile, the other sessile or pedicellate, similar to those 

 of Zea, the glumes firmer; pistillate spikelets solitary (a minute rudiment of a 

 sterile spikelet sometimes found), on opposite sides at each joint of the thick, 

 hard articulate lower part of the same rachis, sunken in hollows in the joints, 

 consisting of one perfect floret and a sterile lemma; first glume coriaceous, 

 nearl} r infolding the spikelet, fitting into and closing the hollow of the rachis; 

 second glume similar to the first but smaller, infolding the remainder of the 

 spikelet; sterile lemma, fertile lemma, and palea very thin and hyaline, these 

 progressively smaller. Robust perennials, with usually broad flat blades and 

 monoecious terminal and axillary inflorescences of 1 to 3 racemes, the pistillate 

 part below, breaking up into bony, seedlike joints, the staminate above on 

 the same rachis, deciduous as a whole. Type species, Tripsacum dactyloides. 

 Name of unknown origin, said by some to come from Greek tribein, to rub, 

 alluding to the smooth joints. 



The species are good forage grasses, but even the more widely spread 

 T. dactyloides is not common enough to be of importance. Two large species 

 not found in the United States, T. laxum Nash and T. latifolium Hitchc, of 

 Central America, are occasionally cultivated for forage in that region. The 

 genus is of interest because it is related to maize. Hybrids between T. dacty- 

 loides and maize have been made. 17 



Staminate spikelets membranaceous, the members of the pair unequally pedicellate, one 



nearly sessile, the other with a distinct pedicel 3. T. lanceolatum. 



Staminate spikelets rather chartaceous, both members of the pair nearly sessile. 



Blades 1 to 2 cm. wide, flat; plants 1 to 2 m. tall; terminal racemes usually more than one. 



1. T. DACTYLOIDES. 



Blades 1 to 4 mm. wide, subin volute; plants less than 1 m. tall; all racemes usually solitary. 



2. T. FLORIDANUM. 



1. Tripsacum dactyloides (L.) L. 

 Eastern gamagrass. (Fig. 1195.) 

 Plants in large clumps, with thick 

 knotty rhizomes, 2 to 3 m. tall or 

 sometimes taller, glabrous through- 

 out; blades usually 1 to 2 cm. wide, 

 flat, scabrous on the margin; inflo- 

 rescence 15 to 25 cm. long, the pistil- 

 late part one-fourth the entire length 

 or less, the terminal racemes usually 

 2 or 3, sometimes only 1, those of the 

 branches usually solitary; pistillate 



11 Mangelsdorf, P. C, and Reeves, R. G. Jour . 

 Hered. 22: 329-343. 1931. Ibid., Texas Agr. Expt. 

 Sta. Bui. 574 (monogr.): 1-315. 1939. 



spikelets 7 to 10 mm. long, the joints 

 rhombic; staminate spikelets 7 to 11 

 mm. long, both of a pair nearly 

 sessile, the glumes rather chartaceous. 

 % — Swales, banks of streams, and 

 moist places, Massachusetts to Michi- 

 gan, Iowa, and Nebraska, south to 

 Florida, Oklahoma, and Texas; West 

 Indies. Tripsacum dactyloides var. 

 occidentals Cutler and Anders. Dif- 

 ferentiated on softer staminate glumes 

 more than 9 mm. long, tapering to 

 an acute tip. % — Texas. Exami- 

 nation of a large number of specimens 

 shows the length and texture of 



